Add test case to prevent regressions to Witness FromIterator
What the developer wrote
Authored by Mitchell Bagot
Add test case to prevent regressions to Witness FromIterator
Following the fix in the previous patch, a simple test case should be
introduced to prevent future changes from introducing regressions on
the extreme length iter edge cases.
What changed, and why it matters
This commit only adds a new automated test. It does not change any production code. The test checks that building a Witness from a very long iterator (over 4 million empty byte slices) does not accidentally drop elements. It is a regression test following an earlier fix, not a security patch itself.
No action required; treat as routine test coverage. Review the prior fix commit if assessing the underlying issue.
Security signals we found
Regression test for prior Witness::from_iter length handling
No production code changes
Evidence from the diff
The diff adds a single unit test, from_iter_does_not_silently_lose_elements, in primitives/src/witness.rs. The test creates a Witness by collecting an iterator of 4,000,001 empty &[u8] references and asserts the resulting Witness length equals 4,000,001. No library code is modified. The commit message explicitly states this is a regression test added after a previous fix.
Changed components
primitives/src/witness.rs (test module only)Inspect captured patch +11 / −0
diff --git a/primitives/src/witness.rs b/primitives/src/witness.rs
index 16d23db7..2995c179 100644
--- a/primitives/src/witness.rs
+++ b/primitives/src/witness.rs
@@ -1314,6 +1314,17 @@ mod test {
assert!(witness4.is_empty());
}
+ #[test]
+ fn from_iter_does_not_silently_lose_elements() {
+ let n: usize = 4_000_001;
+ let witness: Witness = core::iter::repeat(&[0u8; 0]).take(n).collect();
+ let len = witness.len();
+ assert_eq!(
+ len, n,
+ "from_iter silently produced a witness with {len} elements (expected {n})"
+ );
+ }
+
#[test]
#[cfg(feature = "hex")]
fn test_from_hex() {
Why this scored 12/100
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